The present invention relates to techniques of a display device, an electronic device, etc. provided with a touch-sensor function.
Various electronic devices and display devices such as smartphones are equipped with a touch-sensor device (also referred to as a touch panel) as input means. Examples of the touch-sensor device include a touch-sensor device of a capacitive type, etc. Examples of the touch-sensor device include a touch-sensor-equipped display device in which electrodes constituting the touch-sensor function are built in a display panel. Note that the touch-sensor-equipped display device in which the electrodes constituting the touch-sensor function is built in the display panel is also referred to as an in-cell-type touch-sensor-equipped display device. Also, examples of the touch-sensor-equipped display device include a touch-sensor-equipped display device in which the touch-sensor device of the capacitive type is applied to a liquid-crystal display device.
The touch-sensor device of the capacitive type has drive electrodes and detection electrodes as the electrodes which compose the touch-sensor function. In the touch-sensor device, in a surface serving as a touch detection area, for example, the plurality of drive electrodes are parallel to an in-plane horizontal direction, the plurality of detection electrodes are parallel to an in-plane perpendicular direction, and the pairs of the drive electrodes and the detection electrodes mutually intersect, with a distance therebetween, in the perpendicular direction of the surface of the touch detection area. The intersections of the pairs of the drive electrodes and the detection electrodes form capacitors corresponding to units of touch detection. Note that, for the sake of explanation, the units of the touch detection will be referred to as units of detection. In the touch-sensor device, the plurality of units of detection are formed in a matrix pattern in the touch detection area.
The touch-sensor device has a circuit unit connected to the above-described drive electrodes and the detection electrodes. The circuit unit inputs touch-drive signals to the drive electrodes and detects the signals, which are output from the detection electrodes through the units of detection based on the signals. When the capacitance(s) at the unit(s) of detection is changed by a touch with a conductor such as a finger with respect to the surface of the touch detection area, the circuit unit detects the change of the capacitance as an electric signal. As a result, the touch-sensor device can detect the presence/absence, position, etc. of the touch to the touch detection area.
The in-cell-type touch-sensor-equipped display device, for example, has a configuration in which at least one of the drive electrodes and the detection electrodes, for example, the drive electrodes serving as the electrodes constituting the above-described touch-sensor function are built in the liquid-crystal display panel unit. The in-cell-type touch-sensor-equipped display device of this configuration, for example, has electrodes made by integrating common electrodes and the above-described drive electrodes of liquid-crystal display in a TFT (thin-film transistor) board and has the above-described detection electrodes in a color filter board.
As a drive method, for example, a method in which a display period of a display function of the liquid-crystal display and a touch detection period of the touch-sensor function are separated in terms of time to carry out drive is used to the above-described in-cell-type touch-sensor-equipped display device. The drive method using this time division has an advantage that the influence of noise generated from the liquid-crystal display panel unit in the display period does not easily affect the device in the touch detection period.
Conventional technique examples related to the above-described touch-sensor-equipped display device include Japanese Patent Application Laid-Open No. 2009-244958 (Patent Document 1). In Patent Document 1, a configuration example of an in-cell-type touch-sensor-equipped liquid-crystal display device is described.